SMSL SA-S3 TA2021B High-grade HIFI Digital Amplifier + 14V3A Power Adapter - Silver Real 2x25W Stereo design Adopted Air core Inductance which is highly recommonded by Audio fevers,well improved the LC filter circuit. Internal parallelled 9000??F ELNA filter capacitors,well enough to meet the high power of full power working, and solved the problem of disadvantage of bas Built-in Speaker protection & switching on delay circuit, no noise of switching pulse so as to protect your beloved Speakers High-grade Aluminum Shell,drawbench erodegrain Oxidation Process.